SULFIDATED NANOSCALE ZERO VALENT IRON PARTICLE AS WELL AS PREPARATION METHOD AND APPLICATION THEREOF

Abstract

The present disclosure relates to a sulfidated nanoscale zero valent iron particle, as well as a preparation method and application thereof. The preparation method of the sulfidated nZVI particle includes the following steps: 1) ferrous salt is reacted with NaBH4 to prepare nZVI particles; and 2) mixing the nZVI particles with the elemental sulfur powder to prepare the iron sulfides layer-coated nZVI particles. The present disclosure uses elemental sulfur powder as a sulfur source for coating the nZVI particles. The reaction conditions are mild, easy to operate, and the production cost is low. Thus, the technical solution of the present disclosure is convenient for large-scale production, and the prepared sulfidated nZVI particles have high selectivity and reductive transformation capacity for target contaminants, and thus can be used in large-scale remediation of contaminated groundwater or soil.

Claims

1. A preparation method of sulfidated nanoscale zero valent iron (S-nZVI) particles, comprising the following steps: 1) adding a ferrous salt solution to a reactor, further adding NaBH.sub.4 solution to initiate a reduction reaction, then standing for precipitation, removing supernatant, and rinsing a resulted solid to obtain nZVI particles; and 2) dispersing the nZVI particles in a solvent, adding elemental sulfur powder and mixing well, standing for a sufficient period, removing supernatant, and rinsing a resulted solid to obtain the sulfidated nZVI particles.

2. The preparation method according to claim 1, wherein the molar ratio of Fe.sup.2+ to NaBH.sub.4 in step 1) is 1:(4-5).

3. The preparation method according to claim 1, wherein the ferrous salt in step 1) is one selected from ferrous chloride, ferrous nitrate, and ferrous sulfate.

4. The preparation method according to claim 2, wherein the ferrous salt in step 1) is one selected from ferrous chloride, ferrous nitrate, and ferrous sulfate.

5. The preparation method according to claim 1, wherein the ferrous salt solution in step 1) has a concentration of 0.1 to 0.3 mol/L; and the NaBH.sub.4 solution in step 1) has a concentration of 0.2 to 0.4 mol/L.

6. The preparation method according to claim 2, wherein the ferrous salt solution in step 1) has a concentration of 0.1 to 0.3 mol/L; and the NaBH.sub.4 solution in step 1) has a concentration of 0.2 to 0.4 mol/L.

7. The preparation method according to claim 1, wherein the NaBH.sub.4 solution in step 1) is added dropwise to the reactor.

8. The preparation method according to claim 2, wherein the NaBH.sub.4 solution in step 1) is added dropwise to the reactor.

9. The preparation method according to claim 1, wherein the molar ratio of the elemental sulfur powder to the nZVI particles in step 2) is (0.015-0.100): 1.

10. The preparation method according to claim 1, wherein the solvent in step 2) is ethanol.

11. The preparation method according to claim 2, wherein the solvent in step 2) is ethanol.

12. The preparation method according to claim 6, wherein the solvent in step 2) is ethanol.

13. A sulfidated nanoscale zero valent iron (nZVI) particle prepared by the method according to claim 1.

14. The sulfidated nZVI particle according to claim 8, wherein the sulfidated nZVI particle has a particle diameter ranging from 50 to 200 nm.

15. Use of the sulfidated nanoscale zero valent iron (nZVI) particle according to claim 8 in decomposing halogenated organic compounds in wastewater.

16. Use of the sulfidated nanoscale zero valent iron (nZVI) particle according to claim 9 in decomposing halogenated organic compounds in wastewater.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0025] FIG. 1 is a scanning electron microscope (SEM) image of nZVI particles.

[0026] FIG. 2 is a SEM image of sulfidated nZVI particles.

[0027] FIG. 3 is an illustration showing the decomposition of TBBPA by nZVI and S-nZVI.

[0028] FIG. 4 is an illustration showing the dynamic changes of the intermediate products during the decomposition of TBBPA by nZVI.

[0029] FIG. 5 is an illustration showing the dynamic change of the intermediate products during the decomposition of TBBPA by S-nZVI.

[0030] FIG. 6 is an illustration showing the decomposition of TBBPA from different water bodies by S-nZVI and nZVI.

[0031] FIG. 7 is an illustration showing the decomposition of TBBPA by nZVI and S-nZVI of different S/Fe molar ratios.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] The present disclosure will be further explained and illustrated below with reference to specific examples.

Example 1

[0033] A preparation method of sulfidated nZVI particles comprises the following steps:

[0034] 1) Adding 60 mL of 0.2 mol/L FeCl.sub.2 solution to a reactor, adding dropwise 180 mL of 0.3 mol/L NaBH.sub.4 solution to the FeCl.sub.2 solution with stirring; after the dropwise addition, continuing to stir for 15 min, then standing for precipitation, removing the supernatant, and rinsing the resulted solid 4 times with high-purity water to obtain the nZVI particles; and

[0035] 2) Dispersing the nZVI particles in 420 mL of ethanol, adding 0.0096 g of elemental sulfur powder (the molar ratio of elemental sulfur powder to the nZVI particles is 0.025:1), stirring for 12 h, and then allowing to stand for a sufficient period, removing the supernatant, and rinsing the resulted solid 4 times with ethanol to obtain the sulfidated nZVI (S-nZVI) particles.

Performance Test:

1) Morphology Test:

[0036] The nZVI particles prepared in step 1) and the S-nZVI particles prepared in step 2) were dispersed in ethanol, respectively, and were observed by scanning electron microscope (SEM). The obtained SEM images are shown in FIGS. 1 and 2.

[0037] It can be seen from FIG. 1 that the nZVI particles are obviously aggregated in a chain-like structure.

[0038] It can be seen from FIG. 2 that the aggregation of the nZVI particles can be significantly reduced by coating with elemental sulfur powder, and the obtained S-nZVI particles have smaller particle diameters and higher surface roughness.

2) Test on Effects of nZVI and S-nZVI on Decomposition of TBBPA:

[0039] The solution of nZVI particles in ethanol and the solution of TBBPA (tetrabromobisphenol A) in methanol were added to an anaerobic reaction flask, and then deionized water was added to obtain a reaction solution with nZVI of 2.3 g/L and TBBPA of 20 ppm (36.77 mol/L). The reaction solution was stirred at 30 C. At determined intervals, an aliquot of reaction solution was sampled, and 5 mol/L of HCl solution was added to completely dissolve nZVI particles. The reaction between nZVI and TBBPA was terminated, and 1 mL of methanol was added to increase the solubility of TBBPA in the solution. The residual concentration of TBBPA in the sample was determined by high performance liquid chromatography (Shimadzu LC-20A, Japan). The concentrations of various decomposition products of TBBPA in the sample were determined by liquid chromatography-electrospray triple quadrupole mass spectrometry (Agilent LC-ESI-MS/MS). Then a reaction solution was formulated with S-nZVI of 2.3 g/L and TBBPA of 20 ppm, and the S-nZVI particles were tested by means of the same process as that of the nZVI particles. The effects of nZVI and S-nZVI on the decomposition of TBBPA are shown in FIG. 3. The dynamic changes of intermediate products during the decomposition of TBBPA by nZVI are shown in FIG. 4, and the dynamic changes of intermediate products during the decomposition of TBBPA by S-nZVI are as shown in FIG. 5.

[0040] It can be seen from FIG. 3 that, after reacting for 4 hours, the removal rate of TBBPA by S-nZVI reaches 100%, while the removal rate of TBBPA by nZVI is only about 40%. After reacting for 12 hours, the removal rate of TBBPA by nZVI is only about 70%, and is no longer increased, indicating that the effect of S-nZVI on TBBPA removal is more excellent.

[0041] It can be seen from FIG. 4 that after reacting for 24 hours, the decomposition products of TBBPA by nZVI are mainly tribromobisphenol A.

[0042] It can be seen from FIG. 5 that after reacting for 24 hours, the decomposition products of TBBPA by S-nZVI are mainly dibromobisphenol A and monobromobisphenol A, and comprise a small amount of non-brominated product, bisphenol A. It indicates that S-nZVI has excellent debromination effect.

3) Test on Effects of nZVI and S-nZVI on Decomposition of TBBPA in Different Water Bodies:

[0043] The solution of nZVI in ethanol and the solution of TBBPA in methanol were added to a anaerobic reaction flask, and then tap water was added to obtain a reaction solution with nZVI of 2.3 g/L and TBBPA of 5 ppm (9.19 mol/L). The reaction solution was stirred at 30 C. At determined intervals, an aliquot of reaction solution was sampled, and 5 mol/L of HCl solution was added to completely dissolve nZVI particles. Then the reaction between ZVI and TBBPA was terminated, and 1 mL of methanol was added to increase the solubility of TBBPA in the solution. The residual concentration of TBBPA in the sample was determined by high performance liquid chromatography (Shimadzu LC-20A, Japan). The same testing process was applied for investigating the effect of nZVI on the decomposition of TBBPA in groundwater, the effect of nZVI on the decomposition of TBBPA in Pearl River water, the effect of S-nZVI on the decomposition of TBBPA in tap water, the effect of S-nZVI on the decomposition of TBBPA in groundwater, and the effect of S-nZVI on the decomposition of TBBPA in Pearl River water, except that the tap water was replaced with groundwater or Pearl River water, and nZVI was replaced with S-nZVI. The test results are shown in FIG. 6.

[0044] It can be seen from FIG. 6 that S-nZVI has significantly better effect on the decomposition of TBBPA in tap water, groundwater and Pearl River water than that of nZVI.

Example 2

[0045] Referring to the preparation method of Example 1, the molar ratios of elemental sulfur powder to the nZVI particles (abbr. S/Fe molar ratio, which were 0.015:1, 0.025:1, 0.05:1, 0.1:1, and 0.25:1, respectively) were adjusted to prepare S-nZVI with different S/Fe molar ratios. Then, the effects of S-nZVI with different S/Fe molar ratios and nZVI on the decomposition of TBBPA were tested with reference to the test processes of Example 1, and the test results are shown in FIG. 7.

[0046] It can be seen from FIG. 7 that the S-nZVI prepared at the molar ratio of elemental sulfur powder to the nZVI particles of 0.025:1, has the best effect on the decomposition of TBBPA.

[0047] The aforesaid examples are preferred embodiments of the present disclosure, but the embodiments of the present disclosure are not limited thereto. Any alterations, modifications, substitutions, combinations, and simplification made without departing from the scope and principle of the present disclosure should be equivalent alternations, and all are included in the protection scope of the present disclosure.